Question

Find the missing value , if mean is 23.

X	5	15	?	35	45
Frequency	4	8	10	6	2

Answer 1

X	Frequency (f)	fX
5 15 ? (x) 35 45	4 8 10 6 2	20 120 10x 210 90
	Σf = 30	ΣfX = 440+10x

$$\begin{gathered} \overline{X}=23 \\ \overline{X}=\frac{\mathrm{\Sigma }fX}{\mathrm{\Sigma }f} \\ 23=\frac{440+10x}{30} \\ 690=440+10x \\ 250=10x \\ x=\frac{250}{10}=25 \end{gathered}$$
Thus, the missing value of X is 25.